The tool industry currently offers a variety of tools for securing workpieces in industrial, workplace or workshop settings, including vises, bar clamps, C-clamps, and various other types of clamps. Each of these tools have their own specific advantages and disadvantages. For example, a vise provides a strong and sturdy apparatus for securing a workpiece, but is not typically portable and therefore cannot be easily used in multiple locations.
Bar clamps serve as alternatives to a vise in situations where an apparatus for securing a workpiece is required, but the workpiece is at a remote location and/or cannot be placed on a benchtop. Some bar clamps also have the added advantage of being able to be used as both a clamp and a spreader.
Some drawbacks of prior art bar clamps are that the jaws of the clamp members are often not parallel to one another or flush with the workpiece being secured by the clamp. The inability of the clamp jaws to remain parallel to one another and generally perpendicular to the bar is often caused by one of two factors. First, the way in which the movable clamp member is locked into position on the bar of the bar clamp will often cause the clamp member and associated jaw to angle slightly away from or towards the workpiece when the locking mechanism is engaged. For example, in the passive locking bar clamp illustrated in FIG. 14, the movable clamp member 1 is locked into position by simply angling the clamp member 1 with respect to the bar 2, which creates a frictional engagement between the clamp member 1 and the bar 2. The frictional engagement prevents the clamp member 1 from slipping or moving when securing a workpiece. In some instances, the upper and/or lower surfaces of the bar may also be serrated so that the edge of the clamp member opening through which the bar 2 passes catches a tooth of the serrated bar to prevent the clamp member 1 from moving or slipping away from the workpiece. Although this configuration allows for the movable clamp member 1 to be rapidly moved along the bar 2, it angles the jaw 1a associated with the movable clamp 1 and prevents the jaw 1a from remaining parallel to the jaw 3a of fixed clamp member 3 and generally perpendicular to the bar 2.
Similarly, in the locking bar clamp illustrated in FIG. 15, the movable clamp member 1′ is locked into position via a brake plate 1b′ which is biased at an angle to the bar 2′ by a spring to prevent the movable clamp member 1′ and brake plate from being moved about the bar 2′. The movable clamp member 1′ is secured into position on the bar 2′ due to the friction created between the angled brake plate 1b′ and the bar 2′. The bar 2′ may also be serrated so that the edge of the brake plate opening through which the bar passes catches a tooth of the serrated bar 2′ to prevent the clamp member 1′ from moving or slipping away from the workpiece. The biasing of the brake plate into engagement with the bar 2′ often causes the clamp member 1′ and jaw 1a′ to angle with respect to the bar 2′ and with respect to the other clamp member 3′ and jaw 3a′. 
Thus, while the clamp jaws of prior art bar clamps may initially be parallel to one another and flush with the workpiece when positioning the movable clamp member about the bar, the jaw of the movable clamp member typically angles with respect to the other clamp jaw when the locking mechanism of the clamp member is engaged, thereby causing the top of the clamp jaw to no longer be flush against the workpiece.
A second factor preventing the jaws of prior art bar clamps from lying flush against the workpiece or parallel to one another is the fact that the pressure application mechanism, which is necessary to tightly hold the workpiece with the jaws of the bar clamp, is generally located at, or near, the end of at least one of the clamp members. Thus, when pressure is applied to a workpiece using prior art bar clamps, the pressure is concentrated at the top of the clamp which may cause the clamp member and associated jaw to angle slightly with respect to the workpiece, the bar and/or the other clamp member. The angling of the clamp member can prevent the associated jaw from lying flush with the surface of the workpiece and parallel to the other clamp member, which in turn, can make it difficult to clamp the workpiece as desired.
Another shortcoming with respect to prior art bar clamps is that most of the jaws associated with the pressure application mechanism have relatively small surface areas and, thus, do not distribute the pressure over a large surface of the workpiece. The inability to distribute the pressure across the surface of the workpiece often leads to problems such as bowing, warping, and turning of the workpiece, and makes it difficult to accomplish tasks with strict tolerances, such as clamping a workpiece together at a particular angle.
Attempts have been made to overcome some of these shortcomings. For example, European Patent No. EP0010260 B1 discloses a parallel clamp (or body clamp) which has a movable clamp member made up of two pieces, with one piece (14) being secured squarely to the bar (10) and forming a jaw and a second piece (24) being movable about the bar and capable of angling with respect thereto in order to lock the movable clamp member in position. The pressure application mechanism connects the pieces of the movable clamp such that the second piece (24) can be angled with respect to the bar (10) without angling the first piece (14) containing the jaw member. In this manner, the jaws of fixed clamp member (12) and the first piece (14) of the movable clamp member are able to remain parallel to one another and perpendicular to the bar (10).
One shortcoming with the parallel clamp disclosed in EP0010260 B1, however, is that the second piece (24) of the movable clamp member must be tilted or wiggled in order to move the movable bar clamp member along the bar. Moreover, the tilting must be maintained for as long as the movable bar clamp member is moved, otherwise, the second piece (24) will frictionally engage the bar (10) and prevent further movement. This configuration makes it awkward to move the movable bar clamp member along the bar and difficult to move the movable bar clamp member over long distances.
Another shortcoming with prior art parallel clamps is that they do not account for the various positions the clamp may be in when the operator attempts to release the workpiece. For example, in some applications the parallel clamp may be positioned upside down when securing the workpiece or in a position where the pressure application mechanism is not readily accessible. Thereby making it difficult for the operator to release the workpiece.
Yet another shortcoming with existing bar clamps is their inability to interface with other pieces of equipment that are designed to work with specific workpieces. For example, many types of workbenches are designed specifically for woodworking and working with wood workpieces. Existing bar clamps, however, are not designed to interface with these workbenches and fail to take advantage of the unique properties they possess.
Lastly, existing parallel clamps do not adequately account for applications in which a large force must be applied to the workpiece. For example, most (if not all) parallel clamps provide a pressure application member having a fixed handle which requires the operator to twist or rotate the handle in order to apply pressure to the workpiece. Although this type of handle configuration is easy to use when only a small amount of force is being applied to the workpiece, it becomes difficult to twist or rotate when attempting to apply a large amount of force to the workpiece.
Accordingly, it has been determined that the need exists for an improved bar clamp which overcomes the aforementioned limitations and which further provides capabilities, features and functions, not available in current bar clamps.